// ==UserScript==
// @name netflix-speed
// @version 0.8
// @include https://www.netflix.com/*
// ==/UserScript==

function find_controls() {
    return new Promise(function(resolve, reject) {
	var observer = new MutationObserver(function(mutationsList) {
	    mutationsList.forEach(function(mutation) {
		var nodes = Array.from(mutation.addedNodes);
		for (var node of nodes) {
		    if (node.matches && node.matches('.AkiraPlayer') && (node.querySelector('.button-nfplayerNextEpisode') || node.querySelector('.button-nfplayerSubtitles'))) {
			var elem = node.querySelector('.button-nfplayerNextEpisode') || node.querySelector('.button-nfplayerSubtitles');
			resolve(elem.parentNode);
			return;
		    }
		}
	    });
	});

	observer.observe(document.documentElement, { childList: true, subtree: true });
    });
}

function inject_controls() {
    find_controls().then(function(controls) {
	/* remove report a problem button */
	if (document.querySelector('div.ReportAProblemPopupContainer'))
	    document.querySelector('div.ReportAProblemPopupContainer').remove();

	/* don't inject multiple times */
	if (document.querySelector('#speed-control'))
	    return;

	/* create speed_control element */
	var speed_control = document.createElement('div');
	speed_control.innerHTML = `<select>
		<option value=0.5>0.5</option>
		<option value=0.75>0.75</option>
		<option value=1.0 selected="selected">Normal</option>
		<option value=1.25>1.25</option>
		<option value=1.5>1.5</option>
		<option value=1.75>1.75</option>
		<option value=2.0>2.0</option>
		</select>`;
	speed_control.id = 'speed-control';
	speed_control.style.cssText = `
		padding: 0 0 1.68em 0;
		margin: 0 1.5em;`;
	speed_control.firstChild.style.cssText = `
		-webkit-appearance: none;
		background: none;
		border: none;
		font-size: 2.2em;
		text-align: right;`;
	speed_control.firstChild.onchange = function() {
	    document.querySelector('.VideoContainer video').playbackRate = this.value;
	};

	/* inject speed_control element */
	controls.before(speed_control);

	/* redo injection, in case of video change, ... */
	inject_controls();
    });
};

/* initial run of injection */
inject_controls();